Allow tab completion when typing out branch names in the `checkout branch` and `delete branch` tabs.

[H3RSKO]

When a user goes to the Checkout or Delete branch tabs, they need to manually type out the full branch name.

You should be able to type just the first few letters and then hit tab to auto-complete the rest of the branch name.

[vnallamhawk]

is this still open ?

[H3RSKO]

Yup! Want to give it a go?

[sj056]

Hey @H3RSKO ! Is this issue still open and will it be considered for hacktoberfest?

[H3RSKO]

@sj056 Yes! This issue is open and an accepted PR merge would count for Hactoberfest.

[sj056]

Great! I'm working on this issue then.